The authorities said they were struggling to understand the motives for the attack with a car in the eastern city of Magdeburg, in which a 9-year-old boy was among the five victims.
At least five people, including a 9-year-old child, were killed in the attack, which took place in the eastern city of Magdeburg. The authorities are still seeking a motive.
Video showed a car plowing into a large crowd in the city of Magdeburg. The driver, identified as a 50-year-old Saudi Arabian citizen who worked as a doctor, was arrested.
It was not the first online intervention by Elon Musk, the entrepreneur and adviser to Donald Trump, on behalf of once-fringe anti-immigrant parties in Europe.